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| 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file | 1 // Copyright (c) 2014, the Dart project authors. Please see the AUTHORS file |
| 2 // for details. All rights reserved. Use of this source code is governed by a | 2 // for details. All rights reserved. Use of this source code is governed by a |
| 3 // BSD-style license that can be found in the LICENSE file. | 3 // BSD-style license that can be found in the LICENSE file. |
| 4 | 4 |
| 5 library dart.pkg.collection.canonicalized_map; | |
| 6 | |
| 7 import 'dart:collection'; | 5 import 'dart:collection'; |
| 8 | 6 |
| 9 import 'utils.dart'; | 7 import 'utils.dart'; |
| 10 | 8 |
| 11 /** | 9 /// A map whose keys are converted to canonical values of type `C`. |
| 12 * A map whose keys are converted to canonical values of type `C`. | 10 /// |
| 13 * | 11 /// This is useful for using case-insensitive String keys, for example. It's |
| 14 * This is useful for using case-insensitive String keys, for example. It's more | 12 /// more efficient than a [LinkedHashMap] with a custom equality operator |
| 15 * efficient than a [LinkedHashMap] with a custom equality operator because it | 13 /// because it only canonicalizes each key once, rather than doing so for each |
| 16 * only canonicalizes each key once, rather than doing so for each comparison. | 14 /// comparison. |
| 17 * | 15 /// |
| 18 * By default, `null` is allowed as a key. It can be forbidden via the | 16 /// By default, `null` is allowed as a key. It can be forbidden via the |
| 19 * `isValidKey` parameter. | 17 /// `isValidKey` parameter. |
| 20 */ | |
| 21 class CanonicalizedMap<C, K, V> implements Map<K, V> { | 18 class CanonicalizedMap<C, K, V> implements Map<K, V> { |
| 22 final Function _canonicalize; | 19 final Function _canonicalize; |
| 23 | 20 |
| 24 final Function _isValidKeyFn; | 21 final Function _isValidKeyFn; |
| 25 | 22 |
| 26 final _base = new Map<C, Pair<K, V>>(); | 23 final _base = new Map<C, Pair<K, V>>(); |
| 27 | 24 |
| 28 /** | 25 /// Creates an empty canonicalized map. |
| 29 * Creates an empty canonicalized map. | 26 /// |
| 30 * | 27 /// The [canonicalize] function should return the canonical value for the |
| 31 * The [canonicalize] function should return the canonical value for the given | 28 /// given key. Keys with the same canonical value are considered equivalent. |
| 32 * key. Keys with the same canonical value are considered equivalent. | 29 /// |
| 33 * | 30 /// The [isValidKey] function is called before calling [canonicalize] for |
| 34 * The [isValidKey] function is called before calling [canonicalize] for | 31 /// methods that take arbitrary objects. It can be used to filter out keys |
| 35 * methods that take arbitrary objects. It can be used to filter out keys that | 32 /// that can't be canonicalized. |
| 36 * can't be canonicalized. | |
| 37 */ | |
| 38 CanonicalizedMap(C canonicalize(K key), {bool isValidKey(Object key)}) | 33 CanonicalizedMap(C canonicalize(K key), {bool isValidKey(Object key)}) |
| 39 : _canonicalize = canonicalize, | 34 : _canonicalize = canonicalize, |
| 40 _isValidKeyFn = isValidKey; | 35 _isValidKeyFn = isValidKey; |
| 41 | 36 |
| 42 /** | 37 /// Creates a canonicalized map that is initialized with the key/value pairs |
| 43 * Creates a canonicalized map that is initialized with the key/value pairs of | 38 /// of [other]. |
| 44 * [other]. | 39 /// |
| 45 * | 40 /// The [canonicalize] function should return the canonical value for the |
| 46 * The [canonicalize] function should return the canonical value for the given | 41 /// given key. Keys with the same canonical value are considered equivalent. |
| 47 * key. Keys with the same canonical value are considered equivalent. | 42 /// |
| 48 * | 43 /// The [isValidKey] function is called before calling [canonicalize] for |
| 49 * The [isValidKey] function is called before calling [canonicalize] for | 44 /// methods that take arbitrary objects. It can be used to filter out keys |
| 50 * methods that take arbitrary objects. It can be used to filter out keys that | 45 /// that can't be canonicalized. |
| 51 * can't be canonicalized. | |
| 52 */ | |
| 53 CanonicalizedMap.from(Map<K, V> other, C canonicalize(K key), | 46 CanonicalizedMap.from(Map<K, V> other, C canonicalize(K key), |
| 54 {bool isValidKey(Object key)}) | 47 {bool isValidKey(Object key)}) |
| 55 : _canonicalize = canonicalize, | 48 : _canonicalize = canonicalize, |
| 56 _isValidKeyFn = isValidKey { | 49 _isValidKeyFn = isValidKey { |
| 57 addAll(other); | 50 addAll(other); |
| 58 } | 51 } |
| 59 | 52 |
| 60 V operator [](Object key) { | 53 V operator [](Object key) { |
| 61 if (!_isValidKey(key)) return null; | 54 if (!_isValidKey(key)) return null; |
| 62 var pair = _base[_canonicalize(key)]; | 55 var pair = _base[_canonicalize(key)]; |
| (...skipping 44 matching lines...) Expand 10 before | Expand all | Expand 10 after Loading... |
| 107 return pair == null ? null : pair.last; | 100 return pair == null ? null : pair.last; |
| 108 } | 101 } |
| 109 | 102 |
| 110 Iterable<V> get values => _base.values.map((pair) => pair.last); | 103 Iterable<V> get values => _base.values.map((pair) => pair.last); |
| 111 | 104 |
| 112 String toString() => Maps.mapToString(this); | 105 String toString() => Maps.mapToString(this); |
| 113 | 106 |
| 114 bool _isValidKey(Object key) => (key == null || key is K) && | 107 bool _isValidKey(Object key) => (key == null || key is K) && |
| 115 (_isValidKeyFn == null || _isValidKeyFn(key)); | 108 (_isValidKeyFn == null || _isValidKeyFn(key)); |
| 116 } | 109 } |
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